MINERALS

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                   LEARNING OBJECTIVES

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A mineral is a naturally occurring element or compound of elements with a distinct crystalline configuration.

 A mineral is a "naturally occurring element or compound of elements".....

 Minerals are composed of combinations of elements bonded together.
Some consist of only one element: diamond*(C) and graphite* (C) 
Some consist of only 2 or 3 elements: halite* (NaCl) and pyrite* (FeS₂)
Most minerals are more complex: tourmoline* Na(Mg,Fe)₃Al₆(BO₃)₃(Si6O₁₈)(OH)₄
Impurities and substitutions in the chemical formula of minerals are common.....
THEREFORE minerals are defined by their crystal form

 ......"with a distinct crystalline configuration"

 Atoms are the smallest unit of an element. Atoms take up space.
The crystalline configuration or crystal form of a mineral is the result of the "best fit" of all of the atoms of elements that compose a mineral.
A particular mineral will ALWAYS have the same crystal form regardless of size.

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 Polymorphism: two minerals with the same chemical composition but differing crystal forms.

Example:  diamond* and graphite* (the lead in your pencil)  are both composed of carbon. These two minerals have the same composition but are very different from one another because of the internal arrangementof the atoms or crystal form.

Internal arrangement of the atoms or crystal form endows a mineral with specific properties.
You will study each of  these properties in lab.
 

1. Crystal habit: crystal shape of the mineral   (quartzcrystal)*
2. Cleavage: the tendency of a mineral to break along planes of weakness
3. Hardness: how hard the mineral is: Mohs hardness scale and "scratchability"
4. Color: not a good definitive characteristic except for a small number of minerals
5. Specific Gravity: density of the mineral in relation to water
6. Streak: the color of the mineral in the powdered form
7. Other: luster, magnetism, fluorescence

The properties described above can be used to identify and classify minerals.
In lab you will use these properties to identify different minerals.
 

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 There are thousands of minerals. Geologists group minerals into broad categories:

Silicate minerals: those that have silica in their formula,90% of all rock forming minerals. Silica tetrahedron an important part of these minerals.

 During the course of this class in discussing rocks I will use the term ferromagnesium minerals and nonferromagnesium minerals
 
Ferromagnesium minerals: silicates with iron and magnesium in their formula, dark colored and dense. Example includes hornblende.

Nonferromagnesium mineral: silicates with no iron or magnesium in their formula (calcium, sodium or potassium common), light colored. Example includes feldspar.
 

 
1. Carbonate minerals: those that have calcium carbonate in their formula such as calcite.

2. Ore minerals: those that are important resources such as gold and silver.

    

The study of minerals (mineralogy) is complex. In laboratory you will learn to identify some important and common minerals.

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 ROCKS

 Minerals combine to form rocks.
Rocks are classified on the basis of how they were formed.

 Igneous Rocks: form from the cooling of molten rock (lava or magma).

 Sedimentary Rocks: form from small grains of rocks and minerals (sediments) combining at the surface.

 Metamorphic Rocks: form from heat and pressure altering a pre-existing rock without melting it.

 The Rock Cycle illustrates how Earth material is continually recycled over time and as one rock is destroyed, new rocks are formed.